Trunk-piston



P. CHALLIS.

TRUNK PISTON.

APPLICATION FILED MAR. 16, 1920,

1,396, 1 6 1 Patented Nov. 8, 1921.

Pica; 02 (a; ZiWmM- PATENT OFFICE.

PHILIP CHALLIS, OF LONDON, ENGLAND.

TRUNK-PISTON.

Specification of Letters Patent. I

Patented N V. 8 1921.

Application filed March 16, 1920. Serial No. 366,869.

T 0 all whom it may concern.

- they stop short at such a point pistons, more Be it known that 1,.PHILIP GHALLIs, a subject of the King of England, residing at London, England, have invented certain new and useful Improvements in Trunk-Pistons, of which the following is a specification.-

This invention has reference to trunkparticularly intended for internal combustion engines but the invention is applicable to pistons for steam and other engines. In these pistons, it'is known to form the skirt with slots extendingupward from the bottom with a view to obtaining a resilient lowerportion to the piston.

The principal object of vention is to provide a piston the whole of the contact area of which is resilient, flexible, or yielding, the contact area being of such dimensions, and so positioned intermediately of the length of the piston as to prevent penetration of the oil-film under the cross-head resultant thrust. This is attained by providing the contact area with resilient, flexible or yielding contact surfaces which in the free state are preferably of larger diameter than the bore of the cylinder. These contact surfaces are located substantially midway between the upper and lower ends of the piston, so that the gudgeon pin from which the cross-head resultant pressure origmates is comprised between the upper and lower limits of the contact area. The intermediate contact areas do not extend to the lower edge of the piston skirt, but stop shortof that edge; similarly toward the head end as to allow space for the accommodation of the piston rings or the like.

y the present arran ement, having the contact areas substantia ly midway of the length of the piston the latter is maintained at all times co-axial with the cylinder, without looseness of either the head or the lower end, and consequently no tilting of the piston beyond that due tothe yield of the resilient zones as the lateral thrust pressure varies, can take place to cause the piston to pivot and bring its head end vlolently across from one side to the other by reason of the trans fer of the cross-head thrust.

The invention is hereafter described with reference to the accompanying drawings, in .which Figure 1 is an elevation of an alternative constructlon.

' the sides of the the present in-- Figs. 2 and 3 are elevations tion of other constructions.

Fig. 1 represents a form of piston in which the resilient areas are formed as tongues integral with the skirt of the piston but curved outwardly so as to be normally of. greater diameter than the body of the piston. In this construction the skirt is slotted on parallel lines; 03 extending for example over one fourth of the circumference, these slots being connected by two opposite slots 03 which are approximately parallel to the axis of the piston. The edges of the tongues forming slots d general diameter of the piston, so that when sprung into position in the cylinder they exert an outwardly expanding action against the cylinder wall, whereby the piston is held from tilting at the ends of its stroke or from chattering during the stroke. One or more grooves may be cut, for example obliquely as indicated at j to retain lubricant and allow a sufficient degree of flexibility even when a thick gage of metal has been employed.

Fig. 2 shows a piston a having an attached sleeve 0 which is slotted at d to afford resilience in a radial direction to facilitate circumferential expansion and contraction.

in part sec- The sleeve is attached by screw threads 0" at one extremity, its other extremity 0 being free. The slotted portion is of larger diameter than the head end of the piston a, but when inserted in the cylinder the enlarged portion is colla sed to a diameter substantially equal to that of the cylinder. The slots 03 do-not extend to the extremity forming thelower edge of the piston; such edge remains continuous and is of narrower diameter than sleeve. Certain of the slots may intersect or meet at their extremities, so as to afford flexible tongues 0 and they may be of the same width throughout or wider at certain points of their length. The slots may be ended by transverse perforations d through the sleeve or trunk of the piston, and these holes may be used'for connecting together two or more slots as stated above.

Fig. 3'represents a similar construction in which being slotted at d to afford resilience. The upper and lowersleeves are attached to the piston bodyby screw threads 0 at their adj acent extremities, the upper end a ofthe upthe enlarged portion of the two alined sleeves c are provided, bothproject beyond the per sleeve being free to slide upon its supporting surface, and the continuous outer end 0 of the lower sleeve being free. The slots 0? are preferably arranged obliquely to the axis of the piston and of opposite hands in the two sleeves; certain of the slots intersect or meet so as to afford flexible tongues 0 as in the previous construction.

In all cases the diameter of the piston as measured upon the longitudinal plane through the gudgeon pin may be less. than that perpendicular to 1t; the shorter diameter may be over the size of the cylinder or there may be clearance in this direction, the object of the invention being still sufliciently usefully secured by the elimination of clearance at the faces taking the cross-head resultant pressures.

-What I claim is 1. A piston, comprising a head, a body portion, guide-surfaces supported from said body portion, said guide surfaces being slotted on intersecting lines, to form. flexible tongues between the slots in said guide-surfaces, said tongues extending alternately up and down the length of the piston and projecting radially beyond the unslotted portions of saidguide surfaces.

2. A piston, comprising a head, a body portion, guide-surfaces supported from said body portion, said guide surfaces being slotted longitudinally in an oblique direction and the opposite ends of alternate slots con-. nected by intersecting slots, to form flexible tongues between the slots in said guide-surfaces, said tongues projecting radially beyond the unslotted portions of said guidesurfaces.

3. A piston, portion, guide-surfaces supported from said body-portion, said guide-surfaces being slotted on intersecting lines which stop short of the ends of said guide surfaces, to form flexible tongues between the slots in said uide-surfaces, said tongues projecting radially beyond the unslotted portions of'said guide-surfaces.

4. A piston, portion, guide-surfaces supported from said body portion, said guide surfaces being slotted obliquely on intersectin lines to form flexible tongues between tfie slots in said guide-surfaces, said tongues extending lengthwise of the piston and projecting radially beyond the unslotted portions of said guidesurfaces.

5. A piston, comprising a head, a bodyportion, means for the attachment of a piston pin, guide-surfaces adapted to slide on the walls of the cylinder,

comprising a head, a bodycomprising a head, a body-.

said guide-surfaces being slotted obliquely on intersecting lines which stop short of theends of said guidesurfaces, to the slots in said guide-surfaces, said tongues extending lengthwise of the piston above and below the level of said attachment means and projecting radially to a diameter greater than that of the cylinder.

6. A piston, comprising a head, a bodyportion, means for the attachment of a pieton-pin, guide-surfaces connected to said body-portion, said guide-surfaces being di-l vided into ,zones and each of said zones being slotted on intersecting lines which stop short of the boundaries of said zones, to form flexible tongues between the slots in said guidesurface zones, said tongues extending above and below the level of said attachment means and projecting radially beyond the unslotted portions of said guide-surface zones.

7. A piston, comprising a head, a bodyportion, a sleeve secured to said body-portion, said diameter than the cylinder and being slotted lengthwise on intersecting lines whichstop short of the ends of said sleeve, to form flexible tongues between the slots in said sleeve, said tongues projecting radially beyond the unslotted portions of said sleeve.

8. A piston, comprising a head, a bodyportion, means for the attachment of a piston-pin to said body-portion, a sleeve secured internally at about the level of said attach'ment means to said body-portion,'one end of said sleeve being slidably engaged upon said body-portion, said sleeve being divided into zones above and below the level of said attachment means, said zones being slotted obliquely on intersecting lines, to form flexible tongues between the slots in said zones, said tongues projecting radially beyond the unslotted portions of said sleeve.

9. As a new article of manufacture, a piston havin with flexi le tongues affording equalized local pressure on the cylinder walls throughout the whole area of its circumference.

10. As a new article of manufacture, a pisa skirt in the form of a sleeve form flexible tongues between sleeve being of slightly smaller ton having a skirt in the form of a sleeve with intersecting slots extending above and below the level of the piston pin and providlng flexible tongues, said tongues bearing uniformly upon the cylinder walls throughout the circumference of said slotted sleeve. In testimony whereof I have aflixed my signature in presence of two witnesses. 1

PHILIP CHALLIS. Witnesses:

Vrc'ron F. FEENY, OYRIL J. FEENY. 

